JA Solar JAM78S30 590W vs First Solar Series 7 545W
The JA Solar JAM78S30 590W wins this comparison by a decisive margin. It leads in efficiency (22.6% vs 19.8%) and matches or exceeds on warranty (15 vs 10 years). For most residential installations, the JA Solar JAM78S30 590W is the stronger choice.
Key Differences
- • JA Solar JAM78S30 590W is rated at 590W while First Solar Series 7 545W is rated at 545W, a 45W difference.
- • JA Solar JAM78S30 590W achieves 22.6% efficiency vs 19.8% for the other, a 2.8 percentage point gap.
- • JA Solar JAM78S30 590W comes with a 15-year product warranty vs 10 years for the other.
- • JA Solar JAM78S30 590W uses TOPCon N-type cells while First Solar Series 7 545W uses CdTe (Cadmium Telluride) cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The JA Solar JAM78S30 590W achieves 22.6% module efficiency compared to First Solar Series 7 545W's 19.8%, meaning JA Solar JAM78S30 590W converts 2.8 percentage points more sunlight into electricity per square meter. In practical terms, the JA Solar JAM78S30 590W produces 218.2 watts per square meter of panel area while the First Solar Series 7 545W produces 173.9 W/m². For rooftop installations where space is limited, this efficiency gap determines how many kilowatts you can fit on your available roof area. Over a 25-year system life, even a small efficiency advantage compounds into meaningful additional energy production.
Power Output
The JA Solar JAM78S30 590W delivers 590W per panel versus 545W for the First Solar Series 7 545W, a 45W difference per module. To build an 8 kW residential system, you would need 14 JA Solar JAM78S30 590W panels or 15 First Solar Series 7 545W panels. Choosing the higher-wattage option saves 1 panel, reducing total racking hardware, wiring, and installation labor costs. Higher wattage per panel is particularly valuable for commercial-scale installations where panel count directly impacts balance-of-system costs.
Temperature Coefficient
Both panels share an identical temperature coefficient of -0.28%/°C, meaning they lose power at the same rate as cell temperature rises above the 25°C standard test baseline. At 65°C cell temperature, both retain 94.4% of rated power. Neither panel has a thermal performance advantage, which makes this specification a non-factor in the comparison.
Warranty Coverage
The JA Solar JAM78S30 590W is backed by a 15-year product warranty and 30-year performance guarantee, while the First Solar Series 7 545W offers 10-year product and 30-year performance coverage. The JA Solar JAM78S30 590W provides 5 additional years of defect protection, covering manufacturing issues, material failures, and premature performance loss. Based on their published degradation rates (1% first year then 0.4%/year for JA Solar JAM78S30 590W; 1.5% first year then 0.5%/year for First Solar Series 7 545W), after 25 years the JA Solar JAM78S30 590W should retain approximately 89.4% of original output versus 86.5% for the First Solar Series 7 545W. This 2.9 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The JA Solar JAM78S30 590W measures 2384×1134×35mm and weighs 31 kg, while the First Solar Series 7 545W measures 2520×1244×49mm at 38 kg. 2.70 m² of panel area for the JA Solar JAM78S30 590W versus 3.13 m² for the First Solar Series 7 545W. The JA Solar JAM78S30 590W is 7.0 kg lighter per panel, which reduces structural load requirements on the roof and makes handling easier during installation. For a 20-panel system, that is a total weight difference of 140 kg. The more compact JA Solar JAM78S30 590W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | JA Solar JAM78S30 590W | First Solar Series 7 545W |
|---|---|---|
| Power | 590W | 545W |
| Efficiency | 22.6% | 19.8% |
| Power Density | 20.3 W/sq ft | 16.2 W/sq ft |
| Cell Type | TOPCon N-type | CdTe (Cadmium Telluride) |
| Bifacial | No | No |
| Weight | 31 kg | 38 kg |
| Temp Coefficient | -0.28%/°C | -0.28%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 4000 Pa |
| Product Warranty | 15 years | 10 years |
| Performance Warranty | 30 years | 30 years |
| Degradation (Year 1) | 1% | 1.5% |
| Annual Degradation | 0.4% | 0.5% |
| Country | China | United States |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: JA Solar JAM78S30 590WThe JA Solar JAM78S30 590W achieves 22.6% efficiency versus 19.8% — a 2.8 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 1.4 kW more total system capacity, or 7 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: TieBoth panels share a temperature coefficient of -0.28%/°C — identical heat tolerance.
3. Durability & Warranty
Winner: JA Solar JAM78S30 590WJA Solar JAM78S30 590W leads with a 15-year product warranty versus 10 years. JA Solar JAM78S30 590W degrades more slowly at 0.4% per year versus 0.5%. After 25 years, expect 89.4% vs 86.5% of original output for JA Solar JAM78S30 590W and First Solar Series 7 545W respectively.
4. Power Output
Winner: JA Solar JAM78S30 590WThe JA Solar JAM78S30 590W delivers 590W versus 545W per panel — 45W more. For an 8 kW system, you need 14 panels with the higher-wattage option versus 15 panels, saving 1 panels and the associated racking and labor costs.
5. Cell Technology
Winner: JA Solar JAM78S30 590WThe JA Solar JAM78S30 590W uses TOPCon N-type: TOPCon (Tunnel Oxide Passivated Contact) adds a thin tunnel oxide layer to reduce recombination losses, achieving higher efficiency than PERC while being manufacturable on existing production lines. The First Solar Series 7 545W uses CdTe (Cadmium Telluride): CdTe (Cadmium Telluride). TOPCon N-type represents a newer generation technology with a longer performance runway as manufacturing matures.
JA Solar JAM78S30 590W
JA Solar's JAM78S30 is a high-wattage N-type TOPCon module achieving 22.6% efficiency for large-scale installations.
Pros
- + Very high 590W output
- + Excellent efficiency
- + Low temperature coefficient
- + Bifacial design
Cons
- - Very large and heavy
- - Requires heavy-duty mounting
- - Not for small roofs
First Solar Series 7 545W
First Solar Series 7 is a US-made thin-film CdTe module delivering 545W with superior temperature performance and sustainable manufacturing.
Pros
- + US manufactured thin-film
- + Excellent hot weather performance
- + Lower carbon footprint
- + No supply chain issues
Cons
- - Lower efficiency than crystalline silicon
- - Very large and heavy
- - Not for residential roofs
Choose JA Solar JAM78S30 590W If...
- ✓ Your roof space is limited and you need maximum power per panel
- ✓ You want fewer panels to reach your target system size, reducing racking and labor costs
- ✓ Long-term warranty protection is a top priority and you plan to stay in your home for 15+ years
- ✓ You want maximum output retention over the system's 25-30 year lifespan
- ✓ You prefer newer cell technology with a longer performance improvement runway
Choose First Solar Series 7 545W If...
- ✓ Utility-scale projects valuing US manufacturing and hot-climate performance.
Our Recommendation
The JA Solar JAM78S30 590W is the decisive winner in this solar panel comparison, outperforming the First Solar Series 7 545W in 4 of 5 dimensions. Unless you have a specific requirement that the First Solar Series 7 545W uniquely addresses, the JA Solar JAM78S30 590W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, JA Solar JAM78S30 590W or First Solar Series 7 545W?
The JA Solar JAM78S30 590W wins this comparison by a decisive margin. It leads in efficiency (22.6% vs 19.8%) and matches or exceeds on warranty (15 vs 10 years). For most residential installations, the JA Solar JAM78S30 590W is the stronger choice.
Which panel is more efficient, JA Solar JAM78S30 590W or First Solar Series 7 545W?
The JA Solar JAM78S30 590W at 22.6% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 2.8 percentage points translates to approximately 45W per panel under standard test conditions.
Which has a better warranty, JA Solar JAM78S30 590W or First Solar Series 7 545W?
The JA Solar JAM78S30 590W comes with a 15-year product warranty and 30-year performance guarantee. The First Solar Series 7 545W offers 10-year product and 30-year performance warranties. JA Solar JAM78S30 590W provides 5 additional years of product coverage.
Which panel performs better in hot weather?
The JA Solar JAM78S30 590W has a temperature coefficient of -0.28%/°C and the First Solar Series 7 545W is -0.28%/°C. Both handle heat equally. A lower (less negative) temperature coefficient is better.
How many JA Solar JAM78S30 590W vs First Solar Series 7 545W panels do I need for an 8 kW system?
For an 8 kW system: you need 14 JA Solar JAM78S30 590W panels (590W each) or 15 First Solar Series 7 545W panels (545W each). The JA Solar JAM78S30 590W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026